The invention relates generally to EDM machines such as erosive cutting machines and die-sinking machines, and, more particularly, to axial arrangement of such machines, as well as a set of modules for assembly of machine tools.
EDM machines are widespread, for example, in the form of erosive cutting machines and die-sinking machines. In such machines, a machining tool in the form of a wire electrode or cavity sinking electrode is moved relative to a workpiece clamped on a tool board in order to produce an electrical spark discharge between the machining electrode and the workpiece. Such machines include a machine frame with drive kinematics to produce the relative displacement between the workpiece and machining electrode that determines the machining contour, a tool table with appropriate means of clamping to accept one or more workpieces, a generator, a CNC control, as well as devices to rinse the working gap and to process any employed working fluid.
Machine tools, and especially EDM machines, can be used in a variety of ways. Therefore, different designs have been developed over time. Such designs depend on the corresponding requirements, like selling price, maintenance costs, workpiece size and maximum travel, quality, productivity, flexibility and automatability, space requirements, operating comfort, etc. The emphasis in the development of the machine tool can therefore be completely disparate. Such requirements are often at variance, like space requirements of the machine, on the one hand, and maximum admissible workpiece size, on the other. It would be desirable, precisely in the last-named case, to have the most compact design possible, but nevertheless a capability of also machining larger workpieces . These requirements are only met to a limited degree in the designs of EDM machines known thus far.
For example, most available erosive cutting machines have a C-machine frame or a bridge frame. An example of an erosive cutting machine is the C-frame design described in DE 35 24 377 A1 of the applicant. The C-frame is constructed from several blocks, namely, a machine bed, a column and a machine head. The wire electrode is tightened in the working space of the machine between an upper and lower wire guide head and moved relative to the workpiece in an X/Y main axial plane. Different axial arrangements are indicated for this purpose. The main axial movement in the X/Y direction is conducted with a coupled X/Y crosstable, which moves either the work table, the column of the machine frame, or the head of the machine frame in the X/Y main axial directions.
In an erosive cutting machine of the bridge design, the machine frame includes a machine bed and a closed bridge-like column arranged on it. A worktable, together with work tank, is displaceably mounted on the machine bed in a main axial direction, (for example, the Y direction). The X advance movement of the wire electrode is decoupled from it and produced by an X-slide, which can be displaced horizontally on the cross-rail of the bridge column above the work space. This type of bridge machine is suitable for machining large workpieces. However, it also requires correspondingly large set-up space. The work space of the machine is also only marginally accessible, because of the closed design, and therefore only suitable with limitations for integration of automation devices.
Another machine for an erosive cutting machine is described in U.S. Pat. No. 5,243,165, in which the X/Y main axial slides are arranged independently of each other, in similar fashion to the bridge design. The machine frame is constructed in the fashion of a C-frame with a machine bed and a vertical column fastened to it. An X-slide is displaceably arranged in a horizontal plane on the machine bed on which the tool table and work tank sit. The workpiece is, therefore, only moveable in the X direction. A Y-slide, to which the upper and lower wire guide head is coupled, is arranged directly on the machine column and moves only the wire electrode in the Y direction. Another crosstable system (so-called U/V crosstable) arranged directly on the upper wire guide head permits relative deflection of the upper wire guide head relative to the lower one. A Z-drive for the upper wire guide head is additionally provided.
A shortcoming in this design and in the aforementioned C-frame design is that the machine frame, assembled from several parts (e.g., the machine bed, the column, and, optionally, the machine head), does not possess sufficient intrinsic rigidity in the so-called two-or multiblock design with high accuracy requirements. Consequently, the set-up location of the machine must satisfy increased requirements on floor rigidity. For example, the machine column and the machine bed must be provided with multiple supports on the floor. Set up and alignment of such a machine is very demanding. In particular, installation of different components of the machine frame must occur very carefully, so that the orthogonality of the axial movement is fulfilled.
A three-axis cutting machine, in which the X- and Y-slides are moveable independently of each other, is also shown in the journal xe2x80x9cWerkzeug and Formenbauxe2x80x9d, February 1999, page 30. The X-slide is also laterally displaceably arranged on the machine frame in the fashion of a console, and the Y-slide, equipped with a Z-drive, is arranged on the top of the machine frame. However, details concerning the design of the machine frame are not disclosed. Nor is there any indication in the direction of an EDM machine.